Fasteners

ABSTRACT

A fastener receptacle is adapted to receive a rotatable stud having a shank with a pin-like lateral projection thereon and comprises a body with a bore which accommodates the stud shank. The wall of the receptacle is provided with a slot which defines a helical ramp up which the pin-like projection passes during the fastening operation, the pin-like projection being held, by spring-loading of the stud, in a detent at the end of the ramp. Means are provided to attach the receptacle and stud to their respective panels or the like which are to be fastened together.

United States Patent Winslade 1 July 11, 1972 1 FASTENERS 2,884,6775/1959 Zahodiakin ..24/22l K 2,975,667 3/l96l Bross [72] Inventor. 112:2Herbq't Widade, Feltham, En- 3.51822 10/1964 crimhsmm 3 3,169,293 2/1965Neuschotz ..24/22l K 73 Assi ee: Inter-lacked FashnersUmMT k I l hmMiddlmx England FOREIGN PATENTS 0R APPLICATIONS 22 Filed: Dan 4 1970403,659 5/l943 ltaly "24/221 K [2!] Appl. No.: 95,033 PrimaryExaminer-Bemard A. Gelak Attorney-Baldwin, Wight & Brown [30] ForeignApplication Data [57] ABSTRACT g g i g :2: A fastener receptacle isadapted to receive a rotatable stud having a shank with a pin-likelateral projection thereon and comprises a body with a bore whichaccommodates the stud I "K shank. The wall of the receptacle is providedwith a slot which I 58 1 M K 221 R defines a helical ramp up which thepin-like projection passes during he fastening operation the pimfikeprojection being held b s rin -loadin of the stud in a detent at the endof the 6 m Cm a Y P 8 8 I [5 1 Rd ramp. Means are provided to attach thereceptacle and stud to UMTED STATES PATENTS their.h respective panels orthe like which are to be fastened t 2,486,4l l 11/1949 Huelster ..24/22lK use at 3,136,017 6/1964 Preziosi 24/221 K SClahm, 16 Drawing figuresI!!! III llll ll H P'A'TENTEUJUL 11 I972 3.675.280

saw 2 or 3 rxs'rsuaas The present invention relates to a fasteningassembly comprising a receptacle which is adapted to cooperate with arotatable stud, and especially to a novel receptacle for such anassembly.

The present invention provides a receptacle adapted to receive arotatable stud comprising a shank having a pin-like lateral projectionthereon, the receptacle comprising a rigid body having an opening in thebme thered adapted to admit the shank and the lateral projection, a boreleading from the said opening and adapted to receive the shank of therotatable stud, the bore having a lateral extension adapted to receivethe lateral projection, the wall defining the bore having a slot thereinadapted to receive the lateral projection, the lowermost wall of theslot defining a helical ramp the upper end of which terminates in adetent for the lateral projection, and the lower end of which commencesat the lateral extension.

Preferably, the rigid body is, above the base, substantiallycylindrical, the bore extending therethrough substantiallylongitudinally.

The present invention further provides a fastener assembly comprising areceptacle as described above and a rotatable stud having a shank and alateral projection thereon.

The fastener assembly of the present invention is suitable for fasteningtogether two juxtaposed members, each of the members having an aperturetherein so disposed that the apertures are in register when the membersare in fastened relationship. The receptacle is adapted to be securelyattached to one member with the opening in the receptacle body beingcoincident with the said aperture in that member; the rotatable stud isgenerally located in a housing which is secured in the aperture in thesecond member.

Preferably, the fastener assembly comprises a rotatable stud having ashank, a head and a pin-like lateral projection at the end remote fromthe head, a housing for the stud having an aperture therein and a springlocated within the housing, the shank passing through the aperture inthe housing such that the projection is external to the housing, thespring being adapted to oppose advancement of the stud head towards theaperture in the housing.

Generally, the shank is provided with a cross-pin which forms twodiametral lateral projections. The receptacle will generally then beprovided with opposed, but congruent, pairs of lateral extensions,slots, ramps and detents.

To effect fastening of the members one to another, the shank of the studis passed through the opening in the receptacle and along the borethereof. Each lateral projection will travel up a lateral extension tothe bore. When each projection is located adjacent its respective ramp,the stud is rotated to cause the lateral projections to ride up theramps and into the detents. Each detent is conveniently a notch orhollow into which the lateral projection fits after travelling up theramp.

The assembly is especially suited for fastening one panel to anotherpanel or to a frame member, e.g. in aircraft manufacture. The assemblymay be used in internal and external locations.

It has been found that the fastening action can be rendered easier byextending that slot of which the lowermost wall defines the ramp inorder to form the lateral extension to the bore; this obviates the needto "search" for the ramps, i.e. to rotate the stud in order to place theor each projection adjacent its ramp. The slot is extended as far as theopening in the receptacle body. By this means, the or each pin-likeprojection is guided directly to its ramp as the stud shank is insertedinto the receptacle. In order to facilitate this, the leading edge (i.e.the edge facing the wall defining the ramp) of each slot at the entranceto the receptacle is preferably chamfered.

Generally, the stud is provided with a head at its end remote from theprojection or cross-pin. The head may be in the form of a knob, which ispreferably knurled, in order to facilitate rotation of the stud.Alternatively, the head may comprise a kerf so that rotation of the studmay be effected with the aid of a screwdriver or similar implement.

Advantageously, a spring or other means is provided to hold the lateralprojections in the detents. Conveniently, a spring may be located in thehousing of the stud so that it abuts the head of the stud. Movement ofthe projections along the extensions to the bore and up the ramps will,of course, be ef fected against the bias of the spring.

The receptacle may be fastened to its member by any convenient means.For example, the base of the receptacle may comprise an apertured lug orflange to allow fixing to the member by means of a screw or rivet.Alternatively, the base comprises a peripheral flange and a cage may beprovided having side walls defining an enclosure adapted to accommodatethe base, a transverse wall having an aperture therein through which therigid body except the base may pass, the side walls defining a mouthremote from the transverse wall which is large enough to admit the base,a side wall having an apertured lug attached thereto whereby the cagemay be firmly fixed to its respective member with the base held thereinagainst the member. Advantageously the base has a cut-out therein, thecage having a lug on a side-wall thereof lying substantially in theplane of the cage flange, the cut-out being adapted to accommodate thelug, whereby rotation of the rigid body is limited.

A feature of the receptacle of this invention is that the portion of thestud shank above the pin-like projection can be accommodated in thesection of the bore above the ramp, or ramps, and thereby centered andbraced against stresses occurring in a direction other than parallel tothe longitudinal axis of the shank. This arrangement protects thetransverse projection from stress which might distort or even break it.Preferably the section of the bore above the ramp is so dimensioned thatthere is an interference fit of the stud shank in this section. Theshank may be of such a length as to protrude from the aperture where thebore emerges at the top of the receptacle.

It has also been found that the stud shank can be braced againstlongitudinal stresses by the provision of a spring in the receptacle,conveniently in the portion of the bore above the detent, or detents,said spring being adapted to bear upon the stud shank when the latter isin position, thereby maintaining the pin-like projection in its detent.

Presently preferred embodiments and other aspects of the presentinvention will now be described with reference to the accompanyingdrawings, in which:

FIG. 1 is a section through a receptacle and a stud prior to fastening,

FIG. 1 is a side view in the direction of the arrow A of the receptacleof FIG. 1,

FIG. 3 is an underneath view of the receptacle of FIG. 2,

FIG. 4 is a plan view of the receptacle of FIG. 2,

FIG. 5 is a view of the cage shown in FIG. I in the direction of advanceof the stud,

FIG. 6 is a side view of a suitable retaining ring for the stud housingshown in FIG. 1,

FIG. 7 is a longitudinal section through an alternative stud housing tothat shown in FIG. 1,

FIG. 8 is a section through the top portion of a receptacle having aspring therein,

FIG. 9 is a longitudinal section through a further alternative studhousing,

FIG. 10 is a perspective view of the receptacle,

FIG. 11 is a plan view of an alternative receptacle to that of FIG. 1,

FIG. 12 is aside view of the receptacle of FIG. 1 1,

FIG. 13 is a section through line 13-13 of FIG. ll showing a rotatablestud in fastening relationship with the receptacle,

FIG. 14 is an underneath view of the receptacle shown in FIG. 11,

FIG. 15 is a perspective view, partially broken away, of a receptacleand a stud shank having a cross-pin therein, and

FIG. 16 shows yet another alternative form of housing for the stud.

Like parts are indicated by like numerals.

As can be seen in FIG. 1, the receptacle R is secured to a frame 2 bymeans of a cage 3 such that the opening 4 in the base 5 of thereceptacle R is in register with an opening 6 in the frame 2. The cage 3is secured to the frame 2 by means of two rivets 7, each of which massesthrough an aperture 8 in a flange 9 ofthe cage 3.

The panel 10, which is to be fastened to the frame 2 is provided with anaperture 11. A housing 12 is secured in the aperture 11 by means of aretaining ring 13, which engages the housing 12 and which overlies themargin of the aperture 117 Located in the housing 12 is a rotatable stud14 having a shank 15, a head 16 and a cross-pin 17 located in atransverse bore near the end of the shank which is remote from the head16.

The housing 12 comprises an apertured cup 18 through which the shank 15passes. A helical spring 19 is located in the cup 18 and is retained bythe stud head 16; the spring and shank are substantially coaxial. Itwill be seen that to construct the stud and housing assembly, thecross-pin 17 must be inserted after the shank 15 has been passed throughthe spring 19 and the aperture in the spring-cup 18. The cross-pin 17 isconstituted by a hollow metal cylinder having a longitudinal split 20.The split 20 allows the pin to be rolled up slightly and inserted intothe transverse bore. When in place, the pin is allowed to unroll and thethickened ends 21 prevent the pin from sliding out of the bore. Thus,the ends must be separated by a distance not less than the diameter ofthe shank along the transverse bore and they must be larger in diameterthan the transverse bore.

At the mouth of the spring-cup 18 there is formed an external annularshoulder portion 22, on which is formed a cylindrical wall 23 adapted toaccommodate the stud head 16. The flat shoulder 22 lies flush with thesurface of the panel 10 and helps to eliminate rocking of the housing12.

The receptacle R, as can be seen in FIGS. 2-4, comprises a substantiallycylindrical, hollow body 1 on a base 5 of substantially square plan. Thereceptacle is provided with a central bore 24 extending from opening 4in the base 5. The body 1 is provided with two opposed, substantiallylongitudinal slots 25 which extend to the base of the receptacle. At apoint which is a short distance above the base 5, the two walls definingeach slot diverge, one wall 26 being at a small angle to the verticaland extending to the top 27 of the receptacle, the other wall 28 beingat a larger angle to the vertical thereby forming a ramp 29. A hollow 30is provided at the end of each ramp remote from the base: each hollow 30provides a detent for an end 21 of the cross-pin 17.

The two sets of slots, ramps and detents are opposed, but congruent. Thewall 28 extends beyond the hollow 30 forming a substantiallylongitudinal wall 31, which extends to the top 27. Each wall 31 and theimmediately succeeding wall 26 define a column 32; the top 27, which isof annular plan, extends between the two columns 32. The diameter of theannulus 27 is substantially equal to the diameter of the bore 24 at thelevel of the hollows 30.

A curtain 33 depends from the annulus 27. This curtain forms two webs34, each web extending from the inner edge 35 of a wall 26 to the inneredge 36 of the opposing wall 31. Between the two webs 34, the curtain 33forms two lobes 37, each of which is adjacent a respective column 32.This construction enables the production of a receptacle which is lightin weight without undue loss of strength and rigidity. The lower face 38of each web 34 is spaced from its adjacent ramp 29, thereby forming aslot along which an end 21 of the crosspin 17 can travel.

To efi'ect fastening of frame 2 to panel 10 they are brought intojuxtaposed relationship with the spring-cup 18 passing through aperture6 and into the bore 24 of the receptacle R. The stud shank 15 isadvanced along the bore 24 and each end 21 of the cross-pin 1'7 ispassed along a respective slot 25 to the point of divergence of thewalls 26 and 28. On rotating the stud shank 15, the ends 21 of thecross-pin 17 will ride up the ramps 29. The ramps have a camming effectand the stud shank 15 will advance further into the bore 24. The ends 21of the cross-pin 17 are allowed to settle in their respective hollows 30and the spring 19 acting both on the head 16 of the stud l4 and on themargin of the aperture in the housing will keep them firmly seatedtherein. The head 16 of the stud is provided with a kerf 39 to allowrotation of the stud 14 by means of a screwdriver.

As can be seen in FIGS. 5 and 10, the cage 3 comprises a well 40 ofsubstantially square plan. A flange 9 extends from each of two opposedsides of the well 40, each flange 9 being provided with an aperture 8,which allows the cage to be screwed or riveted to a panel, frame or thelike. The bottom 41 of the well 40 is provided with a circular aperture42 through which the body 1 of the receptacle may be passed. The base 5of the receptacle is large enough to ensure that it cannot pass throughthe aperture 42.

Lugs 43 may be provided on the periphery of the well 40. These lugs maybe bent (as indicated in dotted lines in FIG. 5) into a plane parallelto the plane of the flanges 9 and will then be accommodated in thecut-out portions 44 in the base 5, thereby preventing undue rotation ofthe receptacle with respect to the cage 3.

FIG. 6 shows a suitable form of retaining ring 13, namely a washer ofthe intemal shake-proof" type. The washer comprises a flat annular rim45 provided with an internal, crenellated collar 46, which is at anacute angle to the plane of the rim 45. To retain the housing 12, thewasher is forced down around the spring-cup 18 until the rim 45 abutsthe surface of the panel 10, the projections 47 of the crenellatedcollar 46 being in frictional engagement with the spring-cup 18.

The receptacle is preferably die-cast from any suitable material; asuitable material has been found to be an aluminum alloy LMS or LM6. itis possible to employ other metals which can be die-cast, for examplecertain brass alloys or silicon bronze (although the latter may be tooheavy for certain uses). The cross-pin is advantageously made ofoilhardened steel. The stud housing 12 conveniently is also diecast,although a slight saving in weight may be achieved by using a housing ofpressed metal, as shown in F IG. 7. Suitably, both the receptacle andthe housing are anodized. Such an expedient tends to reduce wear on theramp. As an alternative to anodizing, the components may beelectro-nickel plated.

The housing of FIG. 7 comprises a spring-cup 18 connected via an annularshoulder portion 22 to a cylindrical well 48, which is formed with aninternal lip 49. The space 50 enclosed by the lip 49 may be filled withany suitable material, e.g. nylon, to prevent accumulation of watertherein.

In FIG. 8, there is shown in section the end of a receptacle body 1,said end being remote from the base. An apertured, cup-shaped spring 51is located against the annular top 27. The stud shank 15 has an endportion 52 remote from the stud head (not shown), said end portion 52being of smaller diameter than the main shank and defining a shoulder 53in the shank above the cross-pin (not shown). The end portion 52 passesthrough the apertures in the spring 51 and the annular top 27respectively, and is thus centered and braced. The spring 51 acting onthe shoulder 53 supplements the spring 19 in the spring-cup 18 (notshown).

The alternative housing of FIG. 9 is similar in general principle to,and will be assembled in the same manner as, the housing 12. It will beseen, however, than an annular recess 54 is provided for an annularsealing member (not shown) in the shoulder 22 which is to be adjacentpanel 10. The external wall 23 is tapered in shape, to add furtherstability to the housing and also to reduce the risk of damage to thehousing should the wall 23 be knocked.

Referring now to FIGS. 10 to 14, the receptacle illustrated comprises abody 1 having a bore 24. Peripheral lugs 55 are located at the base 5 ofthe body 1 and are provided with holes 56 so that the receptacle may besecured to a frame 2 by means of rivets 7. The receptacle body 1 has anopening 4 in its base 5, which opening is in correspondence withaperture 6 in the frame 2.

Panel which is to be fastened to frame 2 is provided with an aperture11. A housing 12 is secured in the aperture 11 by means of a split ring57 which is located in an annular groove in the housing 12 and whichoverlies the margin of the aperture 11.

Located in housing 12 is a rotatable stud 14 having a shank 15, a head16 and a crossfpin 17 of which only one lateral projection is visible inFIG. 13.

Housing 12 comprises an apertured cup 18 through which the shank passes.A spring 19 is located in the cup 18 and is retained by the stud head16.

The receptacle is provided with two helical slots 58 in the side-wall ofbody 1. The lowermost sides of the slots 58 define ramps 29 whichterminate at their upper ends in notches 30.

The body 1 is provided with an enlarged bore 24' below the lower edges59 of the ramps 29; in other words, bore 24, in this region, is extendedlaterally in order to receive the lateral projections of the cross-pin17 on the stud shank 15. At the level of the lower edges 59 of the ramps29 the lateral extension to the bore is terminated by steps 60, leavinggaps 61 which provided access for the lateral projections to the sideslots 58.

To effect fastening of panel 10 to frame 2, they are brought intojuxtaposed relationship with the spring-cup 18 passing through aperture6 and into the enlarged bore 24' of the receptacle. The stud shank 15 isadvanced along the bore and each lateral projection of the cross-pin 17is passed through a respective gap 61 and into a respective side slot58. On rotating the stud shank 15 the lateral projections of thecross-pin will ride up the ramps 29. The ramps 29 having a cammingeffeet and the stud shank 15 will advance further into the bore 24.

Means may be provided within the receptacle body 1 to guide the lateralprojections into the slots 58 via gaps 61. Conveniently, this may beachieved by vaning or fluting the enlarged bore 24' of the receptacle.

In FIG. 13, the stud shank 15 is shown in the position of maximumadvancement along the bore 24. As mentioned earlier, rotation of thestud may be effected using a screwdriver; the blade 62 of thescrewdriver is shown in FIG. 13,

From the position shown in FIG. 13, the lateral projections of thecross-pin 17 are allowed to settle in the notches 30. The spring 19keeps the projections firmly seated in the notches 30.

In FIG. 15, the receptacle is shown with a stud located therein. Thelateral projections of the cross-pin 17 are seated in the notches 30.The arrow A shows the direction of rotation necessary to cause thelateral projections to ride up the ramps 29 and into the notches 30. Todisengage the stud from the receptacle, all that is required is torotate the stud shank in the direction counter to that indicated by thearrow A together with a slight initial upward movement if necessary. Thecrosspin can be withdrawn through the gaps 61 and the enlarged bore 24.

The receptacle of FIG. 15 is so constructed that the bore 24 terminateswithin the body 1, whereas in the receptacle of FIG. 11 the bore 24opens to the top 27 of the receptacle. In either case, the section ofthe bore 24 which accommodates the portion of the stud shank 15 which islocated above the cross-pin I7 is preferably of such a diameter as toprovide a snug fit for the stud shank. As indicated above, by this meansthe shank is effectively centered and braced against stresses other thanthose occurring in a direction parallel to the longitudinal axis of theshank.

The cross-pin 17 of FIGS. 11-15 is provided by inserting a short lengthof stout wire into a transverse bore in the stud shank. The ends of thewire projecting from the shank are flattened or pinched in order toprovide a transverse dimension greater than the diameter of thetransverse bore in the shank thereby retaining the cross-pin.

Although the housing 12 shown in FIG. 13 has a flared rim 63 surroundingthe stud head 16, it may be desirable to have no part projecting fromthat side of the panel 10 which is remote from the frame 2. This may beachieved. as shown in FIG. 16, by employing a bush 64 to house the stud.A frustoconical skin 66 is provided in the bush 64 to accommodate thefrusto-conical head of the stud; the rim 65 of the skirt 66 lies flushwith the surface of panel 10. A spring 19 may be provided which isadapted to abut the stud head 16 when the stud assembly is in fasteningrelationship with a receptacle, thereby biasing the lateral projectionsof the cross-pin 17 into their respective detents or hollows 30. Thebush 64 may be held in place on panel 10 by means of a split ring 57located in an annular peripheral groove in the bush 64, said split ringoverlying the margin of the aperture 11 in panel 10.

The head 16 may carry any kerf design which is found convenient,including those designs which require special tools to engage the head.

Furthermore, instead of a split ring 57, a semicircular snapring havingits ends turned inwards on a common diameter could also be used. Theends of the snap-ring would be fitted into diametrically disposedexternal recesses in the spring-cup or bush, the rest of the snap-ringoverlying the margin of the aperture 11 in panel 10. If required, awasher could be located between the snap-ring and the margin of theaperture 1 1.

The edge of the flared rim 63 of the housing 12 of FIG. 13 need not abutthe surface of panel 10. If a small clearance between the rim and themember is allowed, undesirable scoring of the surface of member 6 willbe avoided; however, this may be at the risk of lessening the stabilityof the housing 12.

I claim:

1. The combination of a receptacle and a rotatable stud for securingtogether first and second frame members having respective first andsecond openings, said receptacle being pressure-moulded as asubstantially cylindrical hollow body having axially opposite end facesone of which rests upon said first frame member, said hollow body beingin part defined by a central axial bore extending between said oppositeend faces, said body further including a base portion defined by anenlarged peripheral flange including as a portion thereof said one endface, cage means for encompassing and captively uniting said baseportion against said first frame member, means between said base portionand said cage means for preventing relative rotation therebetween, atleast one slot formed in said hollow body, said one slot having anaxially directed portion directed through said one end face, remainingportions of said slot defining a helical ramp terminating at a hollowadjacent to but spaced from a second of said end faces, said hollow bodyat an area above said helical ramp being of a thickness less than toeither side thereof; a housing receiving one end of said stud whileanother end carrying a radial detent projects outwardly thereof, aspring telescopically surrounding said stud at one end and biasing saiddetent toward said housing, and means securing said housing to saidsecond frame member whereby upon telescopic insertion of said housingand stud into said bore said detent respectively travels through saidone end face, said axially directed portion, said helical ramp and comesto rest in said hollow and being retained therein by said spring.

1. The combination as defined in claim 1 wherein said rotationpreventing means are recessed means in said peripheral flange receivinglug means of said cage means.

3. The combination as defined in claim 1 wherein said peripheral flangehas diametrically opposite corners, and said recessed means are disposedat said corners.

4. The combination as defined in claim 3 wherein said recessed means areslots opening into said hollow body.

5. The combination of a receptacle and a rotatable stud for securingtogether first and second frame members having respective first andsecond openings, said receptacle being pressure-moulded as asubstantially cylindrical hollow body having axially opposite end facesone of which rests upon said first frame member, said hollow body beingin part defined by a central axial bore extending between said oppositeend faces, said body further including a base portion defined by anenlarged peripheral flange including as a portion thereof said one endface, cage means for encompming and captively uniting said base portionagainst said first frame member. at least one slot formed in said hollowbody, said one slot having an axially directed portion directed throughsaid one end face, remaining portions of said slot defining a helicalramp terminating at a hollow adjacent to but spaced from a second ofsaid end faces, said hollow body at an area above said helical rampbeing of a thickness less than to either side thereof; a housingreceiving one end of said stud while another end car-

1. The combination of a receptacle and a rotatable stud for securingtogether first and second frame members having respective first andsecond openings, said receptacle being pressure-moulded as asubstantially cylindrical hollow body having axially opposite end facesone of which rests upon said first frame member, said hollow body beingin part defined by a central axial bore extending between said oppositeend faces, said body fuRther including a base portion defined by anenlarged peripheral flange including as a portion thereof said one endface, cage means for encompassing and captively uniting said baseportion against said first frame member, means between said base portionand said cage means for preventing relative rotation therebetween, atleast one slot formed in said hollow body, said one slot having anaxially directed portion directed through said one end face, remainingportions of said slot defining a helical ramp terminating at a hollowadjacent to but spaced from a second of said end faces, said hollow bodyat an area above said helical ramp being of a thickness less than toeither side thereof; a housing receiving one end of said stud whileanother end carrying a radial detent projects outwardly thereof, aspring telescopically surrounding said stud at one end and biasing saiddetent toward said housing, and means securing said housing to saidsecond frame member whereby upon telescopic insertion of said housingand stud into said bore said detent respectively travels through saidone end face, said axially directed portion, said helical ramp and comesto rest in said hollow and being retained therein by said spring.
 2. Thecombination as defined in claim 1 wherein said rotation preventing meansare recessed means in said peripheral flange receiving lug means of saidcage means.
 3. The combination as defined in claim 1 wherein saidperipheral flange has diametrically opposite corners, and said recessedmeans are disposed at said corners.
 4. The combination as defined inclaim 3 wherein said recessed means are slots opening into said hollowbody.
 5. The combination of a receptacle and a rotatable stud forsecuring together first and second frame members having respective firstand second openings, said receptacle being pressure-moulded as asubstantially cylindrical hollow body having axially opposite end facesone of which rests upon said first frame member, said hollow body beingin part defined by a central axial bore extending between said oppositeend faces, said body further including a base portion defined by anenlarged peripheral flange including as a portion thereof said one endface, cage means for encompassing and captively uniting said baseportion against said first frame member, at least one slot formed insaid hollow body, said one slot having an axially directed portiondirected through said one end face, remaining portions of said slotdefining a helical ramp terminating at a hollow adjacent to but spacedfrom a second of said end faces, said hollow body at an area above saidhelical ramp being of a thickness less than to either side thereof; ahousing receiving one end of said stud while another end carrying aradial detent projects outwardly thereof, a spring telescopicallysurrounding said stud at one end and biasing said detent toward saidhousing, and means securing said housing to said second frame memberwhereby upon telescopic insertion of said housing and stud into saidbore said detent respectively travels through said one end face, saidaxially directed portion, said helical ramp and comes to rest in saidhollow and being retained therein by said spring.